Process of making clad metals.



.B. E. ELDHED. PROCESS OF MAKING CLAD u men JAN. 21. 1910. RENE METALS.

WED FEB. 10,1916

Patented Feb. 27, 1917.

APPLICATIO been a desideratum, it has been but UNITED s'rATEs PATENT oFFioIE.

BYRON EELDRED, OF NEW YORK, N. Y., AssIeNoR TO THE COMMERCIAL REsEARcH I comm, A CORPORATION OF NEW YORK. V

PROCESS OF MAKINd GLAD METALS.

Specification of Letters Patent.

Application filed January 21, 1910, Serial NO. 539,245. Renewed February 10, 1916. Serial No. 77,526.

To all whom it may concern.

Be it known that I, BYRON E. ELDRED, a citizen of the United States, now a resident of New York, in the county of Newwith the line of intended union in a sub-- stantially vertical plane, are heated to a temperature equaling but preferably not much above the melting point of. the lower melting metal, and the assembled metals are positively cooled in a. methodical manner,

such cooling being so conducted as to maintain a portion of molten metal under the influence of heat at the uppermost point along the line of'intended union until the completion of such union, solidification of the metal along such line being caused to progress gradually upward; all as more fully hereinafter set forth and as claimed.

It'has long been a desideratum'to produce compound bodies of steel and copper united by a type of union permitting working down the joined bodies together like a unitary body of either metal. Such a type of compound metal is desirable because it permits the union of a substantial coating of copper to a large billet and a subsequent working down to form finished articles, the union being efl'ected once for all in the original large mass. It is also desirable since it permits the production of bodies of steel covered with. non-porousand imperviousf coatings of copper and the like, the

coating being compacted in the working;

something'which it is' not possible to'pro- -.duce by the ordinary methods of electroplating} electrocoatmgs being invariably porous and crystalline. While, as. stated, such compound weld-united bodies have long that it has been possible to make them comunion as does the tact as necessary recently mercially even in round shapes. Copper and steel are metals which are Wholly unlike in their physical and chemical properties and they do not unite readily under ordi'- nary conditions, a body of copper,'for instance, ca'st against a body of steel remaining discrete therefrom and giving no union.

Even where the solid and the fluid metal are both perfectly clean-surfaced, something which it is difficult to obtain in commercial practice, there is no union; there is at most a mere fitting together; an adhesion as distinguished from a cohesion. The two metals often do not seem to come into actual metallic contact and there is no cohesive union between them. No union is so Obtained which will permit the metals being rolled or worked down together as a unitary body however far the co-extension be carried. Recently, however, it has been discovered Patented Feb, 2'7, 191?. i

that a -cohesive'union ofthe desired type may be obtained by the use of a number of expedients, such as the employment of copper at a very high temperature. I have now discovered that the desired type of cohesive union may be eifectedin a much simpler manner.

While it is usually stated that copper and steel have a lack of ailinity for each other at the common casting temperatures of copper, yet this lack of aflinity is not so great as is commonly believed; and in the described ordinary casting operation there are other cooperating causes which militate as even more, against effecting. the sheer weakness of afiinity between the two metals.

lVhen molten copper is cast against steel,

much, or

if the steel be cold or much below the temperature of the copper because of the absorption of heat, such copper solidifies along the line of intended union before there 1s any real o rtunity for the two metals to come into such a metallic and molecular confor cohesive union, .while of course any alloying or interpenetration of the two metals is out of the, question. And subsequent workingwill not improve or form union in'the absence of any initial me tallic union since solid. copper and solid steel do not unite even when compressed into contact with clean surfaces. 'And where any oxid, scale or the like existson the surface of either metal.

, tions which occur in the operation, there is mg exposed to skin cooling,

no opportunity for the escape of the adsorbed layer of gases which solid metals always carry. Molten copper always carries gas which it evolves in solidification and this gas, under the usual conditions of casting, is not permitted Using the stated hot steel core or layer, it is apt to accumulate along the line between the two metals. i

When copper is cast into a mold, Whether containing a body of steel or not, the body of molten metal of course begins to solidify first where heat can escape by radiation and conductionf The site- Walls of the mold bea layer of solid copper forms next them WlIllG at the top of the layer, where air cooling is energetic, another solid layer accumulates. The result is that the evolved gases cannot escape, being imprisoned either Within the mass of copper itself, or, where ahot steel layer is employed, along the bounding lines of the two metals By a simple rearrangement of conditions, this evolving gas can be made an aid in efi'ecting the union rather than a hindrance. As to the way in which the gas operates, 1 cannot at present say, contenting myself with merely noting the fact .that it -appears. to be a help rather than a hindranc 7 Another disadvantage of the stated castpractice is the eroding or ing :method in I Washing action of the heavy body of hot molten metal upon the "surface of the steel where the latter is hot and softened.

l have found that if a body of steel be placed in a mold or receptacle, which is best made of a material which conducts heat freely, such as the newer varieties ofhomo- .geneous and compact graphite, (artificial graphite), and a body of copper. he placed next thereto and the assemblage heated up to the fusing point of copper, but not necessarily or advantageously much above, and

then locally cooled in a special andparticuar manner while maintaining thevheat, co hesively united compound bodies of copper and .steel may be readily attained; such bodies being capable of subsequent co-extension to any extent desired without rupture orv parting of the union and with a substantial 'co-extension in equal degree throughout. Molten copper may be used instead of melting a preformed solid body of copper, such molten copper being cast mto contact with the steel, but its use ofiers an opportunity to escape.

sound and perfect and exhibiting on no advantage and is not as simple, ordinarily. By using a preformed body of solid copper, it can be made clean-surfaced and can be produced in a convenientmanner, While by casting molten copper directl into contact with the steel itself in the mo d the described washing action is apt to take place.

After raising the copper and iron in the mold to the desired temperature, the assemblage is next locally cooled in such a manner that a solidification along the line of union progresses upward from the bottom-most to the topmost metal, the layer of molten metal between .the two metals longer at all upper points along such line than at any lower point. This may be, and advantageously is, accomplished by cooling the base of the metals while maintaining the heat at their top. that the exterior layers, that is those next to the side walls of the mold shall solidity early, but it is not particularly disadvantageous. But it is desirable that the top layer shall remain iiuid longer than the bottom layer and that solidification of the cop per shall progress regularly from below upward. practice this can only be done by continuing the heating of the mold. In so doing the gases the center find a tree vent through the top most, still liquid copper and are able to exercise whatever influnece they may have on the surface of the steel as they rise therealong. Under the described conditions the gas is able to 1rise throughout the mass of still molten metal, and such oxid as may be entangled in the copper or adhering to the surface of the steel can also rise by virtue of its comparatively low specific gravity which is still further lowered by the tendency of the evolving gas to cling to solid particles. It maybe also that in the described operation the carbon on the surface of the steel and the oxygenin the copper react to form further gas and carbonless iron (which unites with copper with comparativereadiness), butas to this lexpress no opinion. At all events,'by performing the described operation in the described manner sound unions are efiected. The copper of the coating also forms an unusually casting, being free of blowholes, porosity, sponginess and the like its outer surface'the exact contour of the mold in which it is produced. w

Where it is desired to use molten copper remaining fluid It is not desirable as they rise and go toward directly, the copper maybe cast in themold next to the properly heated steel and the assemblage allowed to cool under maintenance of top heat in the methodical manner I heat, except in so far asmay be necessary cooled floor until solidification is complete.

in keeping the top layer molten until the last by the stated top heating. Where, as is sometimes convenient, the slab of copper to be used is produced in the mold itself, the steel being placed in position in the mold and the copper cast against it and the Whole allowed. to stand and cool, the assemblage must of course be reheated to melt the copper prior to cooling and solidifying the copper in the described methodical manner. I The present process may be used to produce steel cores coated on all sides such as round bodies having a steel core and an.

annular copper sheath, or it may be used for producing steel bodies faced or coated on less than all sides, as for instance, in making compound bars for sheets carrying the copper on but one face or side. I shall herein after describe it more fully in connection with its application for single faced bodies.

The heating and cooling in the described manner may be performed in a variety of Ways and with a variety of apparatus; One convenient way of cooling after the melting operation is simply'to pass the mold con-" taming he two metals upon a water-cooledbasewhile allowing the heat to continue to play upon the top of the mold. The cooling will insure solidification going upward through the mass against the top heat resulting from the upper portion of the cop per being still exposed to the heat. v

In a simple, cheap and ready method of operation using a reverberatory or like type of furnace, a body of steel may be placed in a container of synthetic graphite with a slab or bar of copper next thereto and the mold placed in the front of the. furnace. The mold may now be pushed along the floor of the furnace from one end to the other and during its progress the copper brought to a state of fusion. After the fusion is com-. plete the mold may be pushed on a special water-cooled floor at the end of the furnace while still exposed to the flames of the furn'ace, thereby securing the desired differential temperature between the top and the bottom. It may. be'retained on this water- By reason of the high conductive power of the copper, theheat abstracted by the cooled lower layer of copper will bring about the water upon it,

final solidification of the top layer 'in spite of the heat playing upon it. In a simpler, the two of the character described, exposed to heat untilthe copperis molten and then without discontinuing the heat the base of the mold may be cooled by dipping inLwater, or sprayair cooling, etci V Upon removal of. the solidified joined metals from the crucible in either method of operation they will be found united with a union of the type described and the copper aluminum-bronze,

'tended for rolling down'to single orwill be found to be an absolutely homogeneous perfect ingot. The present method ,of fusing and cooling may, ,'ndeed, be employed for making soundcopper ingots or castings,

no steel being placed in the mold in this case.

However, where a steel-cased,"copper-cored article is desired, the 3 copper may be so united to a tube mold of steel, the steel for the casing serving also as the crucible or mold. The described method may of course be employed in, making multilayer articles, such as, a layer of steel and a layer of nickel united byla layer of copper. The absolute control of the operation afforded by the relatively low furnace temperatures employed and the fact that the operation may bestopped at a'ny'point makes the process particularly adapted for producing a cohesive union between copper and nickel. Nickel, and particularly the comparatively pure, relatively carbonless varieties of the commercial metal, is apt to alloy and intermix with-the copper in any method involving relative movement of the two metal masses, copper passing into the nickel and nickel into the copper, but by placing a body body of ing the then quickly cooling inthe stated manner no time or opportunity is; afforded for more than a superficial alloylng, which is more or less desirable as No liquid copper need be flowed past the nickel surface with attendant washing and eroding, which is apt tobe serious with these two metals, nor is thereany stirring up or intermingling, as is apt to be the case in dip ping operations.

promoting the union.

While I-have more particularly described my invention with -reference to the union of copper and steel, it is to be understood that it is equally applicable-to uniting copper with nickel, cobalt, iron, the various alloy steels, etc., and indeed may be used with any of the other iron-likeor ferrous metals.

mayalso use other copperlike and cuprous metals such as gold, silver, brass, bronze, etc. in'lieu of the copper layer of an iron-like meta While a regard my process as particularly adapted for making slabs or bars of steel informing compound metals comprismg'acoated-on one or more faces withcopper infaced sheets. and plates, yet, asstated,

also be employed for making rounds intenddouble I it may ed for manufacturing compound wire or other shapes. In such a case, a tubular bodyof copper is substituted for the bar or slab of copper. F or most commercial purposes, the presence of iron in the copper is not disadvantageous, and is even advantageous in proper proportions as giving greater tensile strength, but for wire for electrical purposes there should be substantially no iron in the bulk of the coating. the presence of iron being confined to av thin intermediate layer of linking metal between the steel core and the body of the coating since iron runs down the conductivity of copper to a degree out of all proportion to its sheer amount. Tn making such electrical goods therefore, bodies of substantially pure, substantially iron-free copper should be employed and the operation carefully conducted to avoid any agitation of the body of molten copper or any relative movement of the two metal masses.

ln the accompanying illustration, I have shown more or less diagrammatically, cer tain assemblages of apparatus elements within the present invention and suitable for use inthe described process. In this showing:

Figure l is a vertical containing molds;

section of a. furnace Fig.2- is 'a horizontal section of the same furnace taken along line sen-m of Fig. 1;

Fig. 3 is a vertical section of a simple type of discontinuous furnace showing a mold in position;

F a is a Vertical section of a ried by a shoe; and

Fig. 5 a similar View of a mold. In the structure of Fig. 1,element 1 is a furnace chamber of the reverberatory' type having ashallow recess 2 in its arch and a stack 3 for removing aste gases. Door 4% permits the introduction of the molds 5, each of'whic-h is shown as mounted in a fiat shoe 6 of steel or like material. Pusher 7 engages a train of molds and pushes them along the floor 8 until they reach the Watercooled section 9 opposite door 10 leading (see Fig. 2) to the side chamber 11. A

mold carpair of oil burners 12 are shown as furnishing the heat for the device. e

In Fig. 8, furnace chamber 13, provided with oil burner 14 and lid 15, is shown as. containing a mold carrying a body of copper 16 and a body. of steel 17. Around the mold passes a straplS to permit handling.- The mold rests as shown upon a removable section 19 of the floor of the furnace, this section being carried by ram-20. Annular water pipe 21 permits the projection of coolmgwater upon the base of the mold.

Hold-down means 22 keeps the'steel from rising.

In the operation of the structure of'Fig. 1, 6 molds 5 carryinga bar of steeLor like metal 17 and a bar of copper 16, the'latter being slightly longer to allow for settling, are pushed on the furnace floor through door The pusher 7 engages the steel shoe carrying the bottom of the mold and pushes the mold forward along the pusher being retracted each new mold introduced and the process repeated until there is a train of molds reaching far as the water-cooled floor 9. As this train of molds passes forward along the length the furnace, the copper 16 is brought to the point of fusion and the liquid metal occupiesthe space between 1'? and the sides of the mold. If it be desired to make a copper ingot, the billet or slab 17 is simply omitted. If it be desired to produce steel coated on all sides, then an annular sleeve of copper 16 (see Fig. 5) is substituted for the flat slab 16 and the round billet 17 inserted within it. As the train of molds passes along the length of the furnace, the assembled molds are heated until the copper is brought to the point of fusion, but not necessarily or advantageously much above. The steel is kept from rising or being displaced by 22. The recess 2 in the roof of the furnace produces a concentration of heat at a point just before the water-cooledfioor 9. As each new mold reaches this water-cooled door, it is cooled from below upward by the abstraction. of heat by such water-cooled floor and the copper solidifies from the bottom upward. During this solidification, the heat of the furnace is still playing upon the top of the mold and maintaining the top copper thereby giving the gases an opportunity to rise. The mold is preferably made of some of the'newer varieties of synthetic graphite (as shown in Fig. i), this being a material which conducts heat with comparative readiness while it does not weld with the copper, as would an iron or steel mold. The shoe not only facilitates the absorption of the heat by the floor 9 in the cooling stage, but operation by taking the stress from the pusher. The operation of the structure of Fig. 3 is similar. The mold carrying the two metals is placed on the movable bottom 19 and heated by the flame from 14; until f the copper melts. The mold and movable bottom are now lowered by 20 until the bottom of the mold is below 21, while the head of the mold is still exposed to the flame of ,the furnace. "Water is now'sprayed upon the bottom of the mold, producing a bottom solidificatiom while the heat of the furnace maintains the top layer of the copper molten until the last, An lieu of water,

As iron and steel are mewhat lighter specifically than copper, :is desirable to 'provide hold-down means such as 22 to keep the former metal in place during the operation. a K

molten to the last,

length of the furnace, the

aids in the pushing air blast may be usedin.

'copper plates with a In the showing of Fig. 5, 16' may be taken either as an annular sleeve of copper surrounding round core bar 17 or. as a pair of steel plate between them for making a double-faced article.

.What I claim is:

1. The process, of -making' clad metals which comprises placing a body of a highmelting'ironlike metal in a mold, placing a body of an unlike, non-ferrous high melting metal. of somewhat lower' melting point in contact therewith, raising. the temperature until the second-named metal melts and cooling the mold and contents from below upward byabstraction of heat from the bottom thereof while still-supplying heat to the residue of the mold so that the topmost layer of molten metal shall be the last to solidify.

2. The process of making clad metals which comprises placing a body of a high melting ferrous a mold, placing a metal 111 body of an unlike, non-ferrous high melting metal of somewhat lower melting point in contact therewith, raising the temperature until the second-named metal melts and cool- I ing the mold and contents from below upward by abstraction of heat from the bottom thereof while still supplying heat to the residue of the mold so that the topmost layer of molten metal shall be the last to solidify.

3. The process of making clad metals which comprises placing a body of steel in a mold-placing a body of an unlike, non-ferrous high melting metal of somewhat lower melting point in contact therewith, raising the temperature until the second-named metalmelts and cooling the mold and contents from below upward by abstraction of heat from the bottom thereof while still supthe topmost-layer of molten metal shall be the last to solidify.

4:. The process of inaking clad metals which comprises placing a body of steel ina mold, placing a body of copper in contact therewith, raising the'temperature until such copper melts and cooling the mold and contents from below upward by abstraction of heat from the bottom thereof while still supplying heat to the residue ofthe mold so that the topmost layer of molten metal shall be the last to solidify.

5. The process of producing a sound body of copper which comprises placing a body of copper in' a mold, raising the temperature until such copper melts and'cooling the mold from below upward by the abstractlon of heat from the bottom thereof while still supplying heat to the residue ofthe mold so that the topmost layer of molten metal shall be the last to solidify.

6. The process of which comprises cooling a high-melting ironlike metal producing clad metals body of solid and a body of cooling that the topmost layers of molten metal said floor until the copper melts, and

topmost layers of molten metal shall be the last to solidify. a

, 7. The process of which comprises cooling a body of solid ferrous metal and a body of molten highmelting non-ferrous metal resting in contact therewith-in a suitable mold, the body and such cooling being produced by cooling chilling of the mold and contents and a basal being of molten metal shall be the last to solidify.

8 The process of producing clad metals which comprises cooling a body of solid steel and a body of molten high-melting non-ferrous metal resting incontact therewith in a suitable mold, the body of such mold being exposed to heat during such cooling and such of the mold and contents and being so conducted that the topmost layers of moltenv metal shall be the last to solidify.

9. The process of producing clad metals which comprises cooling a body of solid high-melting ironlike metal and abody of molten cupriferous metal resting in contact being produced by a basalchill-ing such cooling and such cooling being" producing clad metals I of such mold being exposed to heat during such so conducted that the topmost layers therewith in a suitable mold, the body of such mold being exposed to heat during such cooling and such .a basal chilling of the mold andcontents and being so conducted that the topmost layers of molten metal shall be the last to solidify.

10. The process of producing clad metals which comprises coolin'g a body of solid l i g h at t th id f th ld so th t steel and a body of molten cupriferous metal resting in contact therewith in a suitable mold, the body of such mold being exposed to heat during such cooling and such cooling being produced by abasal chilling of the mold and contents and being so conducted be the last to solidify. 11. The process of producing clad metals which comprises cooling a body of solid steel and a body of molten copper resting in contact therewith body of such mold being exposed to heat during such cooling and such cooling being produced by a basal chilling of the mold and contents and being-so conducted that the topmost layers of molten metal are the last to solidify.

'12, The process of forming copper-clad metal which comprises placing a. steel in a thermallyconductive mold, placing a body'of copper in contact'therewith, placing the mold uponthe floor of a shall cooling being produced by I in a suitable mold, the o body of heated furnace,,pushing the mold along the until the copper solidifies While still allowing the furnace flame to heat the top of the mold.

13. The process of forming clad metals which comprises placing a body of one high-melting metal in a thermally conoluctive molchplacing a body of a second highmelting metal having a somewhat lower melting point in contact with the first-named metal pushing the mold progressirely along the floor of a flame heated furnace until the second-named metal melts and then posi tively cooling the bottom of said mold until the latter metal solidifies While still allowing the flame to heat the top of the mold.

1%. The process of forming cast copper which comprises placing a body of copper in a mold, pushing the lllOlCl along the floor of a flame heated furnace until such copper melts and then positively cooling the bottom of such mold until the copper soliclifies While still allowing the fiame to heat the top of the molcl.

15. The process of forming a sound body of copper which comprises cooling and solidifying a body of molten'copper in thermally conductive mold exposed to high heat, said cooling being performed by abstraction of heat from the bottom of the mold While the rest of the molol is still e2:- posecl to heat so that the topmost layers of molten metal shall be the last to solidify.

16. The process of forming a sound body of copper which comprises basally anal posi tively cooling a body of molten copper in a thermally conductive mold While exposing like metal in a mold in a chamber at a temperature above the melting point of saicl copper-like metal and while said mold and contents are still eXposecl to the heat in said chamber, producing a forced cooling and solidification ofs'aid molten metal by cooling applied to the base of said mold.

In testimony whereof, ll afix my signature in the presence of Witnesses.

BYRGN E. ELDRED. lVitnesses JOHN A. River A. Mi Sen or.

a contacting vertical layer of molten copper- '1 

